Electric lamp and process of making the same



March 28, 1939 c. .1. BRIEFER I 2,151,686

ELECTRIC LAMP AND PROCESS OF MAKING THE SAME Filed June 8, 1955 INVENTOR.

ATTORNEY.

Patented Mar. 28, 1939 .UNlTED STATES PATENT OFFICE ELECTRIC MMPIQIIIVEDARfiJESS OF MAKING Caesar J. Briefer, New York, N. Y. Application June 8, 1935, Serial No. 25,592

2 Claims.

This invention relates to electric lights. It is an object of this invention to produce an electric lamp having a great bulk of the light projected in one direction but which, nevertheless, permits 5 an ornamental distribution in the reverse direction. It is a further object to devise a method of producing such a lamp which is commercially practical and economical and which results in a lamp of high quality.

It is a further object to providea tool by which the improved lamps may be economically and satisfactorily made.

It has heretofore been proposed to produce electric lamps which embody in themselves refiectors of various kinds by having reflecting material either coated upon or attached to the glass of. the lamp, but the method to manufacture adopted has been either too expensive for commercial production or the lamps have been too fragile for use.

Moreover it has been heretofore commerciallyto produce a lamp having a. durable silver reflecting surface upon the interior of the bulb.

It isan object of this invention to provide a lamp which for illuminating purposes will cause substantially a total concentration of the useful illuminating rays in the direction desired and which at the same time will cause an attractive distribution of selected rays through the reflecting surface.

The invention accordingly comprises an article ofmanufacture possessing the features, properties, and the relation of elements which will be exemplified in the article hereinafter described and the scope of the application of which will be indicated in the claims.

, The-invention accordingly comprises the'sev-- eral steps and relation and order of one or more of such steps with respect to each of the others, and the article possessing the features, properties, and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description, taken in connection with the accompanying drawing, in which:

The figure represents a lamp made in accordance with thisinvention.

In the drawing, the numeral I designates a bulb which as illustrated is of the type generally known as the mushroom type carrying a filament impossible,

2, supportedupon a suitable stem 3, and connected to a base 4, in the usual manner.

In accordance with this invention, a lreflecting surface, as for example a metallic silver deposit 5, is applied to the interior of the bulb in the 5 form of a translucent coating which covers only that portion of the bulb toward which it is not desired to direct the illumination, the remainder of the bulb as shown at 6 being clear.

Suggestions made heretofore to coat the surl0 face of a bulb with silver have not been practical in manufacture or successful in the market, and such lamps have not been attractive when used in fixtures. p

In accordance with this invention, I have found 15 that a coating of a thickness which is partially transparent will reflect substantially all of the rays required for illumination and yet at. the same time impart to the remainder of the bulb a purple glow which is quite attractive. 0

I have also found out a practical and commercial way of constructing this lamp which improves its appearance and reduces its cost over the processes which have heretofore been suggested to produce a reflecting surface on the in- 25 terior of a bulb.

In accordance with this process. the lamp is coated throughout its inner surface with a coating of silver deposit, but this coating is stopped at a point where the coating itself is still trans- 30 lucent. For different purposes different thicknesses of coatings may be employed, but in general I prefer to deposit a coating which will transmit a beautiful violet colored light. I have found that such a coating will reflect the i1lumi- 35 nating rays as well as a thicker coating, selecting as it does only the shorter wave lengths for transmission.

Even, however. when it is desired to make the coating opaque it will not require a very great 40 increase in the thickness of the coating, which may still be of a very minute and physically inappreciable thickness. Such a thickness may, for convenience, be referred to as the order of thickness of translucence, to distinguish it from the 45 materially heavier coatings which have been commonly used, as for example for coatings placed upon the exterior of a bulb. Such a coating is more durable upon the inside of the glass as compared with the thicker coatings which tend ing to peel off from the glass under the heat of the filament.

After the coating is applied, I insert any suitable soft tool and rotate it relative to the bulb in contact with the silversurface, to rub off the silver from a portion of the bulb, leaving the bulb partly coated and partly free. In this manner the coating can be left with a sharply defined edge which adds to the appearance of the lamp both when illuminated and when not illuminated.

The glass bulb so made is then employed in the manufacture of an incandescent lamp in accordance with customary practices by sealing in the fllament supporting stem, exhausting the lamp, and then attaching thereto the customary base.

For many purposes of indirect illumination it will be found desirable to frost the bulb over its clear portion so as to diffuse the light and break up any tendency that it would otherwise have to focus any spots or streaks.

Where this frosting is desired, however, it should preferably be applied to the exterior of the lamp, otherwise the silver deposit and the frosting might interfere with each other.

In the drawing, the lamp is shown with the reflecting material on that portion of the bulb which is toward the stem, leaving the outer end free from the silver. It will be clear, however, that the reverse may equally well take place, namely, that the bulb should be frosted upon its outer end, the frosting being removed on the side toward the stem.

Since certain changes in carrying out the above process and certain modifications in the article which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Since certain changes in carrying out the above process and certain modifications in the article which embody the invention may be made without departing'from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to' be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

What I claim and desire to secure by Letters Patent is:

1. The process of making a bulb for an incandescent lamp having a reflecting surface upon the glass which comprises depositing a silver coating upon the interior of the bulb over a substantial portion of said bulb and thereafter removing the deposit from that portion of the bulb which is tobe transparent.

2. The process of making a bulb for an incandescent lamp having a reflecting surface upon the glass which comprises depositing a silver coating upon the interior of the bulb over a substantial portion of said bulb and thereafter removing the deposit from that portion of the bulb which is to be transparent by mechanical rubbing off of the deposited coating upon that portion of the bulb.

CAESAR J. BRIEFER. 

